This application is a continuation in part of application Ser. No. 08/296,212. The present invention relates to methods and apparatus for automating the process of making continuous fiber products, such as chopped fiber, rovings, etc.
In the manufacture of chopped fiber, such as glass fiber, molten glass is extruded through tips or holes in the bottom of a metal box or bushing, forming beads at the end of the tips (normally tips are used, but it is also feasible to use a tipless bushing having only holes or holes on raised portions lands on the tip plate--it is to be understood that when the term "tips" is used hereafter what is intended is any of these configurations used to make fiber). When the beads reach a certain size, the surface tension, wetting, and viscosity forces holding the bead to the bottom of the tip are overcome by gravity and the beads fall, trailing a continuous, coarse, primary fiber behind each bead which is attached at its other end to the molten glass in the tip or hole from which the bead came. The primary fibers are usually sprayed with a cooling water mist after they move out of the immediate area below the tip plate of the bushing in a known manner.
Once all of the tips or holes have thus "beaded out", the array of primary fibers from that bushing is ready to be gathered into a fiber bundle, i. e. a strand, and fed into a chopper or other device that will pull the strand of fibers fast enough to attenuate the molten portion of each fiber to the desired fiber diameter and will also chop, wind or otherwise process the strand or strands of fibers into a desired product form. After a bushing has been in service a few weeks or months, the tips get out of alignment with the cooling means and often a few tips will have a lower molten glass flow rate than the other tips. To accelerate the bead down time of these tips the operator will move the array of primary fibers back and forth to attach the slow beads to primary fibers and pull them down to get a primary fiber from all tips and a strand ready to start. Until the primary fibers are started into a puller, chopper, winder, etc., they usually continue to move and fall into a scrap pit or area beneath the floor of the fiber forming room.
The portion of the continuous fiber making process of starting a strand of fibers from all of the tips of a bushing and of transporting and starting strands of fibers into choppers or other processing equipment has always been done by hand and is labor intensive. Thus it is desirable to automate, or partially automate, this portion of the process, not only to reduce labor cost, but more importantly to increase the percentage of time each bushing is making fiber products and to reduce primary fiber waste.
For a number of possible reasons, fibers tend to break all to frequently, usually near the end of the tips in the bushings. Particularly with E type glass, when one fiber breaks it is usually only a matter of a few minutes until the entire bushing is broken out and generating scrap primary fibers. Even in cases where broken fibers do not form beads or break out the remainder of the bushing, by design, it is nevertheless prudent to break out the entire bushing and restart it after a small number of fibers have broken to maximize efficiency and to reduce variation in the product being produced.
Typical methods used in the industry to make continuous chopped fiber products are disclosed in U.S. Pat. Nos. 3,815,461, 4,194,896 and 4,576,621 and the disclosures in these patents are hereby incorporated by reference. In a typical method an operator would stand below and in front of a fiber forming bushing to be restarted. If a part of the bushing is still running good fibers, the operator would break out that portion. As soon as all of the tips have beaded out and primary fibers are being generated from all of the tips, the operator gathers the array of fibers together into a bundle or strand, cuts or breaks the strand to form an end and pulls the fiber array against a sizing applicator and the strand under a pad wheel or guide with a curved surface below the bushing and walks the strand, pulling it, down to a puller, such as a chopper or winder, and feeds it into the pulling mechanism whereby the strand is pulled at the proper speed and chopped continuously into chopped fiber product or wound into a continuous strand package for use in making reinforced plastics, non-woven fiber glass mats, etc. In a typical operation each operator may have responsibility for 10 to 30 or more bushings and each bushing start may require walking at least 20-40 feet to get the strand to the puller or chopper, and in some instances, to the winder, and to walk back to the position or the next position needing attention or starting.
With many bushings typically breaking out (at least 20 fibers broken) at least 1-4 times per hour, especially when the glass quality varies from normal, the operator either doesn't have time to start each bushing as soon as necessary for most efficient operation, or the operator becomes tired and doesn't get the bushings restarted timely. This resultant loss of efficiency and the desire to reduce the labor costs in this process makes it desirable to automate the most labor intensive portions of these processes.